The present invention relates to telecommunications and more particularly to packet switched networking systems capable of carrying voice traffic.
Recent legislative changes in the United States have promoted competition in the telecommunication industry and spurred demand for new services at lower prices. These trends are pressuring major telecommunications carriers to increase capacity while reducing the cost of providing service. Consequently, major carriers around the world are looking to packet technologies, such as Internet Protocol (IP), frame relay, and Asynchronous Transfer Mode (ATM), to replace circuit-switched technologies in the Public Switched Telephone Network (PSTN) for providing voice capability. In addition, IP, frame relay, ATM, and other packet-based technologies offer narrow-band and broad-band services to selected customers on the same network, providing the same platform for integrated voice, data, and video services from low bandwidth to very high bandwidths.
Over the decades, however, major voice carriers have invested heavily in developing a Signaling System 7 (SS7) signaling and switching infrastructure to offer reliable telephone service. This infrastructure includes countless systems for billing, provisioning, maintenance, and databases that are compatible only with SS7. These systems are commonly referred to xe2x80x9clegacy systems,xe2x80x9d a term that also includes other proprietary protocols such as ISDN_PRI, DPNSS, ISUP, TUP, NUP, H.323, and SIP. Due to the substantial investment in the legacy systems, it is desirable to keep the legacy systems in operation, yet still take advantage of the newer packet technologies.
Moreover, certain demographic trends are motivating telephone call carriers to integrate their legacy systems with packet-switching networks. Certain countries are known to generate an above-average amount of long-distance telephone traffic. For example, residents of Israel are known to consume long-distance telephone services at a rate far greater than the average of residents in other industrialized nations. Long-distance telephone services carried over the PSTN are expensive. Voice calls carried over the globally accessible packet-switched network known as the Internet, however, are generally free. Accordingly, local telephone companies and other call access providers in certain countries are acutely interested in finding ways to integrate the PSTN with the Internet.
These legacy systems, however, do not handle the protocols for the newer packet-switching networks, and, the newer packet-switching network protocols in common use are incompatible with one another. Therefore, there is a need for signaling protocol that can handle call-control information between gateways that join the PSTN or legacy systems and a packet-switching network, notwithstanding the protocol employed by voice calls arriving at the gateways.
These needs, and other needs that will become apparent from the following description, are addressed by the present invention, which implements a common signaling protocol that unifies protocols for various legacy and newer systems for communicating voice calls transparently over a packet-switched network. As used herein, a xe2x80x9cvoice callxe2x80x9d refers to both the signaling information necessary to establish and tear down a voice connection (i.e., a communication link satisfying bandwidth, latency, and quality of service requirements for near toll quality voice communication) and the voice data borne over the voice connection. Voice data includes human voice as well as data embedded in a voice signal, such as modem data, and facsimile data. The voice signaling, associated with the voice data, can be embedded in the same channel as the voice data, time-division multiplexed with the voice data on the same physical line or channel, or present on a separate channel from the voice data.
In particular, the common signaling protocol specifies that messages include a network-wide call identifier that allows a voice call to be uniquely identified throughout the network. Accordingly, signaling units that employ this common signaling protocol can be provided within the network for handling signaling interworking and protocol conversion (if necessary) of the legacy systems. The voice data is handled by coding units. The call identifier in the common signaling protocol enables the voice signaling to be extracted from the voice call, processed separately from the voice call, and rejoined at the terminating site, in a network having a number of different logical and physical implementations of virtual switching sites. Thus, a flexible solution for integrating with legacy systems is attained because voice signaling processing is separated from voice data handling.
One aspect of the invention involves a telecommunication network that includes a packet-switching network, such as an IP, ATM, or frame relay network, coding units coupled to the packet-switching network and signaling apparatuses coupled to the coding units, respectively, and to each other. At least one of the signaling units is configured to receive signal data for establishing a voice call, generate messages encapsulating the signaling data in accordance with a signaling protocol, and transmit the message to another one of the signaling units. Each message in accordance with the signaling protocol includes a call identifier that uniquely identifies the voice within the packet-switching network.
In some modes of operation, each message in accordance with the signaling protocol includes a network address of either or both of the signaling units. In addition, some of the messages include an information element that contain a connection descriptor indicating information about a connection managed by a coding unit, such as the network address of the coding unit and/or a virtual circuit identifier.
Another aspect of the invention pertains to a signaling apparatus, a computer-readable medium, and a method for establishing a voice call through a packet switching network. The signaling apparatus receives signaling data for establishing the voice call, generates messages encapsulating the signaling data in accordance with a signaling protocol, and transmits the messages to another signaling apparatus. Each message in accordance with the signaling protocol includes a call identifier that uniquely identifies the voice within the packet-switching network.
Yet another aspect of the invention relates to a telecommunications signal structure in accordance with a signaling protocol and bearing a message for establishing a voice call over the packet switching network. The message contains a header that includes a call identifier that uniquely identifies the voice within the packet-switching network and a body that includes signaling data for establishing the voice call.